//2009/08/13 19:21:15
#include <string>
#include <vector>
#include <map>
#include <queue>
#include <sstream>
#include <algorithm>

using namespace std;

class TransportCounting
{
public:
    int countBuses(int speed, vector <int> positions, vector <int> velocities, int time)
    {
		int count = 0;
		int ours = speed * time;
		for(int i=0; i<positions.size(); i++)
		{
			if(positions[i] == 0) 
			{
				count ++;
				continue;
			}
			else if(positions[i] + time * velocities[i] <= ours) count ++;
		}
		return count;
    }
};
